Device and circuit for the ignition of fluorescent lamps



E. SCHULER 2,711,489

DEVICE AND CIRCUIT FOR THE IGNITION OF FLUORESCENT LAMPS June 21, 1955 2 Sheets-Sheet Filed July 10, 1952 n l m 0 l I l l I I I I n o 20 nun mr June 21, 1955 E. SCHULER 2,711,489

DEVICE AND CIRCUIT FOR THE IGNITION OF FLUORESCENT LAMPS Filed July 10, 1952 2 Sheets-Sheet 2 C U 4 Cl f 1? PM qwavrap Ewwt 607L1/0Z67 DEVICE AND CIRCUIT FOR THE IGNITION OF FLUORESCENT LAMPS Ernst Schiiler, Siegen, Germany Application July 10, 1952, Serial No. 298,032 2 Claims. (Cl. 307-132) This invention relates to fluorescent lamps and more 1 particularly to the ignition of such lamps at very low temperatures.

With the devices hitherto known for the ignition of fluorescent lamps it is impossible to ignite fluorescent lamps at lower temperatures than C. It is known that a reliable ignition is not possible below -14 C. so that these known ignition devices cannot be used for such purposes as street lighting under the application of fluorescent lamps, in climates Where lower temperatures than l4 C. occur.

Furthermore, it is known that the surges of the presently used igniting devices are irregular. Since they are not controlled they usually occur at unfavorable points of the voltage curve. This is the reason for the fact that the fluorescent lamps cannot be ignited at temperatures lower than -l4 C. and that the insufiiciently controlled surges only result in a continuous flicker of the lamps.

To eliminate said disadvantages it is, therefore, the object of the present invention to provide igniting devices and circuits in such a way that standard type fluorescent lamps can be reliably ignited also at temperatures lower than C.

According to the invention the reliable ignition at very low temperatures, in particular under -l4 C. is efiected in that the necessary surges are generated on the one hand by an oscillating circuit consisting of an inductance and capacitance and on the other hand by controlling the surges in such a way that they occur at the most favorable point of the voltage curve.

A preferred form of the igniting device and of the circuit in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Fig. 1 is a section through the igniting device.

Figs. 2 and 2a represent a schematic circuit of the igniting device.

Figs. 3-8 represent other schematic circuits.

The device preferably consists of a light metal housing 1 which is expediently connected to a cap 2 consisting of insulating material in such a way as to ensure a dust pro-oi covering of the mechanism arranged in the housing The cap 2 supports a yoke member 4 consisting of sheet metal which is connected to a contact pin 3 mounted at the exterior of said cap 2. A condenser 5 is expediently fixed at the free end of the yoke 4. In front of the condenser 5 a magnet coil 6 is arranged on and fastened to the yoke 4 the core of which is provided with two slits at one end wherein a short circuited copper winding is fitted.

To the yoke 4 there is fixed by means of a little block it) made of insulating material one end of a bimetallic contact spring 7 around the free end of which a heating coil 8 is arranged. in order to enable a correct adjustment of the bimetallic contact spring 7 a stop plate 11 is arranged above it against which the bimetallic contact spring 7 is rested. The one end of the stop plate 11 is also fastened in the little insulating block 10.

States Patent 0 2,711,489 Patented June 21, 1955 The bimetallic contact spring 7 and a holding spring 14 the end 13 of which is also fixed at yoke 4 make con tact in the position of rest. For the adjustment of the contact the holding contact spring 14 rests against a stop plate 15 the one end 22 of which is rigidly connected with the end 13 of the holding contact spring 14. An armature 16 is fixed at the holding contact spring 14 which is adjusted in such a way that it will be still attracted by the magnet coil 6 at a voltage of about v. On the other side of the magnet coil 6 a Working contact spring 17 provided with an armature 13 is fixed at the yoke 4.

In order to avoid an excessive movement of the working contact spring 17 a stop plate 21 is provided against which the working contact spring 17 rests in the rest position. A contact face 15 is arranged at the free end of the working contact spring 17, which face 19 will be brought into conductive connection with an opposite contact 26 of the magnet coil 6 if said magnet coil 6 is energized.

The Working contact spring 17 is adjusted in such a way that it is attracted and repelled in every half period of the alternating field of the magnet coil 6 beginning at a voltage of about to v. If the voltage is lower than 160 to 170 v. the working contact spring 17 will stay in the position of rest as shown in Fig. 1. By means of this kind of adjustment and arrangement a very simple conductive connection of the various elements is achieved which can be effected as follows:

The contact pin 3 is conductively connected with the yoke member 4. Furthermore, the holding contact spring 14, the working contact spring 17 as well as one pole of the condenser 5 and one end of the winding of the coil are conductively connected with yoke 4. To a second contact pin 3a are conductively connected: the

opposite contact 2t being insulated from yoke 4, the other end of the magnet coil 6, the second pole of the condenser 5, and the free end of the heating coil 8. The other end of the heating coil 8 is directly connected to the bimetallic contact spring 7, e. g. by means of soldering, or the like. A resistor winding 5a of approximately 30 ohms is arranged in series with condenser 5.

According to the circuit represented in Figs. 2 and 2a the device operates as follows:

After a short preheating of the electrodes ignition is efiected by periodical surges generated by charging and shortcircuiting of the condenser 5 in connection with inductance L.

After closing the fluorescent lamp circuit the filament current for the electrodes flows through the heating coil 3 and through the contacts of the springs 7 and 14 thereby heating the bimetallic contact spring 7. Condenser 5 and winding 6 are shortcircuited. Due to the heating etlect the bimetallic contact spring 7 opens the contact between 7 and 14. When the contact is opened almost the full rated voltage is applied to the winding 6. Hereby the holding contact spring 14 is quickly attracted. The working contact spring 17 is attracted simultaneously and begins to oscillate, operating like an interrupter between the contacts 19 and 20. The

holding contact spring i4 is adjusted in such a way that it will not follow the short interruptions. When the ignition is effected the burning voltage of the lamp lies across the terminals of the winding 6. The holding contact spring 14 stays attracted and the Working contact spring 17 remains in the open position.

Hereafter other circuits and ignition devices will be described by means of which fluorescent lamps can be ignited at low temperatures, in particular under 14 C.

According to the circuit as shown in Fig. 3 the necessary surges for the ignition of the fluorescent lamps are generated by an oscillating circuit consisting of inductance L andcapacitance C, so that the device operates as follows:

The current flowing through the capacitance C, the incandescent electrodes, and the condenser C heats the incandescent electrodes and the voltage of the oscillating circuit generated simultaneously thereby ignites the fluorescent lamp very quickly.

The ignition according to Fig. 4 is effected in the same Way as described for Fig. 3. But here, the condenser of the oscillating circuit is disconnected by means of an interrupter U. in order to improve the reliability of the ignition said interrupter U is designed in such a way that it efiects a periodical interruption during the igniting process, thus generating an additional increase of the igniting voltage.

Hereby, the following operation process is obtained:

When the ignition is efiected the voltage across the terminals of the lamp drops to its rated value. Then the interrupter U opens the circuit and disconnects the condenser of the oscillating circuit, whereby the interrupter U can be controlled either by the lamp voltage or by the lamp current.

The ignition according to Fig. 5 is effected fundamentally as represented and described in Fig. 4. The moment of interruption, however, is fixed by means of phase shifting in such a way that a peak value of additional igniting voltage is generated when the current of the oscillating circuit is interrupted.

The ignition according to Fig. 6 is effected fundamentally in the same way as shown in Fig. 4 or Fig. 5, respectively. The incandescent electrodes of the lamp, however, are hereby preheated by means of a separate relay with retardation. This circuit operates as follows: A thermal relay ThR connected parallel to the lamp opens the filament circuit after a short preheating period after which the ignition device according to Fig. 4 or Fig. 5 begins to operate, thereby effecting the ignition of the fluorescent lamps.

According to the circuit shown in Fig. 7 the filament circuits of the lamp are interrupted by means of contact 1t: after a short preheating of the filament. The contact 1a is controlled by an electrically driven control device, e. g., a small motor. Then, high ignition voltage impulses are supplied to the lamp by means of contact 2a being also operated by the control device, thus effecting the ignition of the lamp.

The contacts can be operated by means of cams, contact rollers, or the like. When the ignition is effected the control device is disconnected by means of current or voltage relay operated by the lamp current or by the lamp voltage in such a way that it stops in its initial position.

The ignition according to the circuit as shown in Fig. 8 is effected in such a way that a time retarded relay is effecting the preheating process and an electro-magnetic interrupter then generates the necessary voltage increase for the ignition. The circuit operates as follows: The contact In is closed in its position of rest so that primarily a filament current for the preheating of the filaments can flow. After the time retarded opening of the contact 1a surges are generated immediately by means of relay R2 controlled by the voltage across the terminals of the lamp, as shown in Fig. 8, or by the lamp current in that the filament circuit is opened and closed in quick succession whereby the lamp is reliably ignited. When the ignition is effected the contacts stay in the open position.

By means of the devices and circuits described igniting devices are obtained for the standard type fluorescent lamps which ensure reliable ignition even at very low temperatures up to approximately C. This effect is attained by providing an optionally controlled preheating process for the filaments of the fluorescent lamps.

it will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim:

1. A device for the ignition of fluorescent lamps comprising in combination a light metal housing, an insulating cap rigidly secured to said housing to close same in a dustproof manner, a yoke member made of sheet metal having two unequal legs and attached to the cap intermediate said legs; two externally mounted terminals on said cap for connection to the starter terminals of a fluorescent lamp; a condenser and resistor in series connected across said terminals, said condenser being fastened on the longer leg of the yoke; a magnet coil arranged adjacent the condenser on the yoke and connected across said terminals; a bimetallic contact spring provided with a heating coil connected between one end of the magnet coil and a contact carried by said spring; a holding contact spring fixed at one end to the yoke and supporting an armature, said holding contact spring normally making contact with the contact of the bimetallic spring, said holding contact spring being permanently electrically connected to the other end of the magnet coil; a working contact spring conductively connected with said other end of the magnet coil and supporting a second armature and a contact element; an opposite contact connected on said one end of the magnet coil and adapted to make contact with said contact element for the passage of current when attracted by said magnet coil, both said armatures being mounted for attraction by said magnet coil when the coil is energized.

2. The invention according to claim 1, wherein the bimetallic contact spring, the holding spring, and the working contact spring are supported against stop plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,394,436 Frech Feb. 5, 1946 2,399,557 Martines Apr. 30, 1946 2,606,235 Penk Aug. 5, 1952 

